Spin-orbit-torque magnetoresistive random access memory with voltage-controlled anisotropy

Abstract

Methods and apparatus relating to spin-orbit-torque magnetoresistive random access memory with voltage-controlled anisotropy are disclosed. In an example, disclosed is a three-terminal magnetic tunnel junction (MTJ) storage element that is programmed via a combination of voltage-controlled magnetic anisotropy (VCMA) and spin-orbit torque (SOT) techniques. Also disclosed is a memory controller configured to program the three-terminal MTJ storage element via VCMA and SOT techniques. The disclosed devices improve efficiency over conventional devices by using less write energy, while having a design that is simpler and more scalable than conventional devices. The disclosed devices also have increased thermal stability without increasing required switching current, as critical switching current between states is essentially the same.

Description

INTRODUCTION[0001]This disclosure relates generally to electronics, and more specifically, but not exclusively, to methods and apparatus relating to spin-orbit-torque magnetoresistive random access memory with voltage-controlled anisotropy.[0002]Random access memory (RAM) is a ubiquitous component of modern digital circuit architectures. RAM can be a standalone device, or can be integrated in a device that uses the RAM, such as a microprocessor, microcontroller, application specific integrated circuit (ASIC), system-on-chip (SoC), and other like devices. RAM can be volatile or non-volatile. Volatile RAM loses its stored information whenever power is removed. Non-volatile RAM can maintain its memory contents even when power is removed.[0003]Magnetoresistive Random Access Memory (MRAM) is a non-volatile memory technology having response (read and write) times comparable to volatile memory. Data stored in MRAM does not degrade over time and, compared to other RAM technologies, MRAM use...

AI Technical Summary

Benefits of technology

[0012]In another example, provided is an apparatus including a memory controller configured to write data to a three-terminal spin-orbit-torque magnetoresistive memory having a magnetoresistive tunnel junction (MTJ) including a free layer located between an oxide barrier layer and a substantially planar spin hall-effect material. The memory controller is configured to apply a first voltage across the MTJ to reduce a magnetic anisotropy of the free layer by inducing an electric field across the oxide barrier layer. The memory controller is also configured to apply a second voltage across the substantially planar spin hall-effect material to cause a curren...

Problems solved by technology

Volatile RAM loses its stored information whenever power is removed.

Despite the characteristics described above, conventional MRAM devices are not perfect.

The shared read and write paths create problems for read speed and write reliability.

However, a thin barrier layer is more susceptible to dielectric breakdown due to repeated write operations.

Also, a state of an MTJ can be flipped unintentionally by a read current.

This is called a “read disturbance.” As MTJ technology scales down in physical size, switching current tends to decrease.

However, high-speed read operations typically require more read current.

Therefore, high-speed MRAM, and particularly deeply-scaled MTJ devices, may suffer from a read disturbance,...

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